1. Field of the Invention
The present invention relates to a technology for rotating display image according to posture, inclination and the like of the device.
2. Description of the Related Art
Some information processing devices with a display, such as smart phones, tablet PCs and the like, include function of rotating to the display image output on the display (auto rotation of the display image) according to the inclination (posture) change of the device. This allows a user to fit the size of the displayed content to a vertically-long screen or to a laterally-long screen to adjust the width and the size of the display content. As is known, the posture of the information processing device is detected with a gravity sensor mounted to the information processing device. According to the detection result, the direction of the display image is controlled such that the bottom side of the display image is positioned on the lower side in the direction of gravity acceleration.
The control method as mentioned above, however, has a problem in that in a situation where the user is lying holding the information processing device, the posture of the information processing device is not stable and the display image may be rotated in a direction not intended by the user.
In order to solve the problem, there is a conventional art of mobile terminal device disclosed in Japanese Patent Application Laid Open No. 2012-058332. When it was detected that the mobile terminal device has moved to the lower position in a vertical direction over a constant distance, the mobile terminal device locks the auto rotation of the display image. In particular, in a case where the terminal information device has moved to the lower position in a vertical direction over a constant distance, it is determined that the user laid down. Then, the mobile terminal device locks the auto rotation of the display image. This prevents the display image from being rotated after locking the auto rotation of the display image even the posture of the information processing device is not stable.
According to the mobile terminal device disclosed in Japanese Patent Application Laid Open No. 2012-058332, it is possible to lock the auto rotation of the display image caused after the movement of the device. It is noted that, in an attempt to move the device, the auto rotation may be caused in the process of the movement. For example, in a case where the user places the device on a desk, the user first touches the outer right side of the device on the horizontal surface of the desk. Then, the user moves down the device in such a manner that the back surface of the device touches the desk. This is a natural behavior for the user to gently put the device on the desk. It means that the user is not intended to change the orientation of the display image. On the other hand, even in this case, the display image may be rotated automatically according to inclination of the device generated by the touch of the right edge of the device to the desk. As described above, there leaves a problem in that, during the movement of the device, the display image is automatically rotated in a direction not intended by the user.